Applications of the electron transfer photochemistry of iminium salt systems to natural product synthesis are being explored. Synthetic routes for preparation of selected members of the harringtonine alkaloid family, which employ photocyclization processes of N-trimethylsilyl substituted allyl iminium salts to construct the key spirocyclic unit, will be developed. Novel, electron transfer induced, photo-carbocyclization processes will be probed as part of efforts focused on the development of efficient sequences for erythrina alkaloid synthesis. Photocyclization reactions of dihydroisoquinolinium salt-benzyltrimethylsilane systems will be employed in general synthetic routes for construction of selected members of the protoberberine, spirobenzyl, aporphine and proaporphine class of isoquinoline alkaloids. Finally, electron transfer pathways for carbocyclic ring annulation will be probed.